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FreeBSD-SA-08:04.ipsec                                      Security Advisory
                                                          The FreeBSD Project

Topic:          IPsec null pointer dereference panic

Category:       core
Module:         ipsec
Announced:      2008-02-14
Credits:        Takashi Sogabe, Tatuya Jinmei
Affects:        FreeBSD 5.5
Corrected:      2008-02-14 11:49:39 UTC (RELENG_5, 5.5-STABLE)
                2008-02-14 11:50:28 UTC (RELENG_5_5, 5.5-RELEASE-p19)
CVE Name:       CVE-2008-0177

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

I.   Background

The IPsec suite of protocols provide network level security for IPv4
and IPv6 packets.  FreeBSD includes software originally developed by
the KAME project which implements the various protocols that make up
IPsec.

II.  Problem Description

There is an improper reference to a data structure in the processing of
IPsec packets, which can result in a NULL pointer being dereferenced.

III. Impact

A single specifically crafted IPv6 packet could cause the kernel to panic,
when the kernel had been configured to process IPsec and IPv6 traffic.

This requires IPSEC to be compiled into the kernel, it does not necessarily
have to be configured at that point.

IV.  Workaround

No workaround is available, but kernels which does not include IPsec
support are not vulnerable.  The GENERIC and SMP kernel configurations
distributed with FreeBSD releases do not include IPsec support.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 5-STABLE, or to the RELENG_5_5
security branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 5.5 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch http://security.FreeBSD.org/patches/SA-08:04/ipsec.patch
# fetch http://security.FreeBSD.org/patches/SA-08:04/ipsec.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_5
  src/sys/netinet6/ipcomp_input.c                                 1.7.4.2
RELENG_5_5
  src/UPDATING                                            1.342.2.35.2.20
  src/sys/conf/newvers.sh                                  1.62.2.21.2.21
  src/sys/netinet6/ipcomp_input.c                             1.7.4.1.4.1
- -------------------------------------------------------------------------

VII. References

http://www.kb.cert.org/vuls/id/110947
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0177

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-08:04.ipsec.asc
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